Infection with Japanese encephalitis virus (JEV) induces high morbidity and mortality, including potentially permanent neurological sequelae. However, the mechanisms by which viruses cross the blood-brain barrier (BBB) and invade into the central nervous system (CNS) remain unclear. Here, we show that extracellular HMGB1 facilitates immune cell transmigration. Furthermore, the migration of immune cells into the CNS dramatically increases during JEV infection which may enhance viral clearance, but paradoxically expedite the onset of Japanese encephalitis (JE). In this study, brain microvascular endothelial cells (BMECs) were utilized for the detection of HMGB1 release, and leucocyte, adhesion, and the integrity of the BBB in vitro. Genetically modified JEV-expressing EGFP (EGFP-JEV) and the BBB model were established to trace JEV-infected immune cell transmigration, which mimics the process of viral neuroinfection. We find that JEV causes HMGB1 release from BMECs while increasing adhesion molecules. Recombinant HMGB1 enhances leukocyte-endothelium adhesion, facilitating JEV-infected monocyte transmigration across endothelia. Thus, JEV successfully utilizes infected monocytes to spread into the brain, expanding inside of the brain, and leading to the acceleration of JE onset, which was facilitated by HMGB1. HMGB1-promoted monocyte transmigration may represent the mechanism of JEV neuroinvasion, revealing potential therapeutic targets.

中文翻译：

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脑微血管内皮细胞衍生的 HMGB1 促进单核细胞粘附和迁移，促进 JEV 神经侵袭。


日本脑炎病毒（JEV）感染会导致高发病率和死亡率，包括潜在的永久性神经系统后遗症。然而，病毒穿过血脑屏障（BBB）并侵入中枢神经系统（CNS）的机制仍不清楚。在这里，我们证明细胞外 HMGB1 促进免疫细胞迁移。此外，在乙脑病毒感染期间，免疫细胞向中枢神经系统的迁移急剧增加，这可能会增强病毒清除率，但矛盾的是会加速日本脑炎（JE）的发病。本研究利用脑微血管内皮细胞（BMEC）体外检测HMGB1的释放以及白细胞、粘附和BBB的完整性。建立表达 JEV 的转基因 EGFP (EGFP-JEV) 和 BBB 模型来追踪 JEV 感染的免疫细胞的迁移，模拟病毒神经感染的过程。我们发现 JEV 会导致 BMEC 释放 HMGB1，同时增加粘附分子。重组 HMGB1 增强白细胞-内皮粘附，促进 JEV 感染的单核细胞跨内皮细胞迁移。因此，JEV成功地利用受感染的单核细胞扩散到大脑中，在大脑内部扩张，并导致JE发病加速，而HMGB1促进了这一过程。 HMGB1 促进的单核细胞迁移可能代表 JEV 神经侵袭的机制，揭示潜在的治疗靶点。